Fix #160 Add DaysSerializer (#161)

Author: JooHyukKim

src/main/java/com/fasterxml/jackson/datatype/joda/JodaModule.java

@@ -46,6 +46,7 @@ public JodaModule()
         addSerializer(Interval.class, new IntervalSerializer());
         addSerializer(MonthDay.class, new MonthDaySerializer());
         addSerializer(YearMonth.class, new YearMonthSerializer());
+        addSerializer(Days.class, new DaysSerializer());
 
         // then key deserializers
         addKeyDeserializer(DateTime.class, new DateTimeKeyDeserializer());

src/main/java/com/fasterxml/jackson/datatype/joda/ser/DaysSerializer.java

@@ -0,0 +1,28 @@
+package com.fasterxml.jackson.datatype.joda.ser;
+
+import java.io.IOException;
+
+import org.joda.time.Days;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.SerializerProvider;
+
+/**
+ * Serializer for Joda {@link Days} class.
+ *
+ * @since 2.19
+ */
+public class DaysSerializer
+    extends JodaSerializerBase<Days>
+{
+    private static final long serialVersionUID = 1L;
+
+    public DaysSerializer() {
+        super(Days.class);
+    }
+
+    @Override
+    public void serialize(Days value, JsonGenerator gen, SerializerProvider provider) throws IOException {
+        gen.writeNumber(value.getDays());
+    }
+}

src/test/java/com/fasterxml/jackson/datatype/joda/ser/DaysSerializationTest.java

@@ -0,0 +1,31 @@
+package com.fasterxml.jackson.datatype.joda.ser;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.joda.time.Days;
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.joda.JodaTestBase;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class DaysSerializationTest extends JodaTestBase
+{
+    final ObjectMapper MAPPER = mapperWithModuleBuilder().build();
+
+    @Test
+    public void testPeriodSerialization()
+        throws Exception
+    {
+        Days days = Days.days(7);
+        Map<String, Object> map = new HashMap<>();
+        map.put("days", days);
+
+        String json = MAPPER.writeValueAsString(map);
+
+        assertEquals("{\"days\":7}", json);
+    }
+
+}